Most studies that have fueled alarm over the attrition and mobility rates of high-quality teachers have relied on proxy indicators of teacher quality, which recent research finds to be only weakly correlated with value-added measures of teachers' performance. We examine attrition and mobility of teachers using teacher value-added measures for early-career teachers in North Carolina public schools from 1996 to 2002. Our findings suggest that the most-effective teachers tend to stay in teaching and in specific schools. Contrary to common expectations, we do not find that more-effective teachers are more likely to leave more-challenging schools. (Contains 17 tables, 1 figure and 15 notes.)